FeCo-MOF derived Co4S3/Fe3S4/MoS2 nanosheet arrays on iron foam for overall water splitting in alkaline water /seawater at large-current density

The exploration of highly efficient noble metal-free catalysts for overall water splitting in alkaline water/ seawater at large-current density is critical for industrial application. In this work, FeCo-MOF derived hierarchical Co4S3/Fe3S4/MoS2 nanosheet arrays on iron foam (IF) were prepared as efficient electrocatalyst for both HER and OER by solvothermal method. The CFM 0.3 nanosheet arrays exhibited the high HER performance with the Tafel slope of 70 mV dec-1 and extremely low overpotential of 241, 377 mV at 100 and 500 mA/cm2. The CFM 0.7 nanosheet arrays can deliver a high current density of 100 and 500 mA/cm2 at the overpotential as low as 220 and 305 mV and small Tafel slope (79 mV dec-1) for OER. Moreover, CFM0.3/CFM0.7 exhibited the low overpotentials of 270/380 mV for HER/OER at 100 mA/cm2 in simulated seawater. The CFM0.3//CFM0.7 delivered comparatively low cell voltage of 1.26/1.45 V at 10 mA/cm2 with excellent stability for 48 h in alkaline water/simulated seawater. Benefiting from the three-dimensional nanosheet arrays framework and the interface coupling interactions of trimetallic sulfides, the self-supporting robustness electrodes with abundant multimetallic electroactive centers can regulate charge/ion diffusion path and electronic structure for prompting HER and OER activity at high current density. Hence, this work would provide new ideas for exploration of highly-active MOF-derived non -noble metal bifunctional catalysts for energy-related applications.